[Vlive] Fix error when trying to download some videos

[kyuyeunk]

Please follow the guide below

• You will be asked some questions, please read them carefully and answer honestly
• Put an x into all the boxes [ ] relevant to your pull request (like that [x])
• Use Preview tab to see how your pull request will actually look like

---

Before submitting a pull request make sure you have:

• At least skimmed through adding new extractor tutorial and youtube-dl coding conventions sections
• Searched the bugtracker for similar pull requests
• Checked the code with flake8

In order to be accepted and merged into youtube-dl each piece of code must be in public domain or released under Unlicense. Check one of the following options:

• I am the original author of this code and I am willing to release it under Unlicense
• I am not the original author of this code but it is in public domain or released under Unlicense (provide reliable evidence)

What is the purpose of your pull request?

• Bug fix
• Improvement
• New extractor
• New feature

---

Description of your pull request and other information

This addresses issue #226 .

Analyzing the code, I found out that for certain links (e.g., https://www.vlive.tv/post/0-18301951), GET request from url https://www.vlive.tv/globalv-web/vam-web/video/v1.0/vod/<video_id>/inkey results in the follow error: {"data":9113,"error_code":"VIDEO_LEGACY"}

Comparing with the request url from a browser, I was able to deduct that gcc=KR is needed from request url to get a proper response from the server.

However, I am not certain what `gcc=KR`` implies.
It might imply a region (i.e., KR=Korea), and maybe some region locking was applied to the video.

[kyuyeunk]

Closing this PR as #245 incorporates the fix, making this PR obsolete.